The present invention relates to an image display device, to a method of generating a correction value of an image display device, to a program for generating a correction value of an image display device, and to a recording medium recording the program thereon.
In a fixed-pixel-type image display device, such as a projector, a liquid crystal monitor, or a plasma display, when an image is displayed by an image generating device paired with a screen on which the image is displayed, there is a case in which output characteristic values, such as a brightness output value or a color output value, in a part of the image displayed on the screen are distributed in a non-uniform manner. At this time, the non-uniform distribution is recognized as the brightness non-uniformity or color non-uniformity of the image displayed on the screen. It is considered that the brightness non-uniformity or the color non-uniformity is caused by, for example, manufacturing errors of elements forming pixels of an image generating device, such as a liquid crystal light valve.
Since the brightness non-uniformity or the color non-uniformity can be solved by correcting an electrical signal providing the distribution of an output characteristic value in a pixel unit, various correction methods have been proposed in the related art.
For example, JP-A-2000-284773 (FIG. 1, paragraphs of [0024] to [0029]) discloses a technique in which the color non-uniformity is corrected according to the gray-scale level by storing correction data corresponding to respective gray-scale levels with respect to the entire image displayed on a screen beforehand, dividing the screen in the shape of a check board, and applying the correction data for each of the divided portions of the image, in order to determine the amount to correct the color non-uniformity of the image displayed on the screen.
Furthermore, as another example, JP-A-2000-316170 (FIG. 2, paragraph of [0068]) discloses a technique in which the color non-uniformity of an image is corrected by dividing the image displayed on a screen into triangle elements, generating correction data at the apices of the triangle elements, and interpolation-generating correction data within the triangle elements by using the correction data at the apices of the triangle elements.
However, the techniques disclosed in JP-A-2000-284773 and JP-A-2000-316170 are realized by dividing a display image into uniform polygon elements and correcting the display image within each of the divided elements but have following problems.
That is, since the screen should be divided into a number of elements so as to obtain a high-quality image by improving the correction precision, the amount of correction data stored in, for example, a look-up table of an image display device becomes large. As a result, a problem arises in that a large-capacity memory is required to store such look-up table.
On the other hand, in order to make the amount of correction values as small as possible, it can be considered that an image is divided into large polygon elements and correction values corresponding to a small number of divided elements are stored in a look-up table. However, in this case, since the correction performed by using the correction values is not apt to be sufficient, it is not possible to correct the image in high precision. As a result, there is a problem in which significant improvement of the image quality can not be expected. In particular, there is a high possibility that the brightness non-uniformity, the color non-uniformity, or the like, which is locally concentrated, will not be reliably corrected.